VCCA Home Forums TECHNICAL - 1945 AND NEWER 1946-1948 1946 won't idle

1946 starts and runs but it WILL NOT idle at the normal idling speed/range . Keeps dying. It will start right up again, run several seconds, then sputter and quit. Took carb off, cleaned, replaced a couple gaskets, everything looks good. New : coil, spark plugs, condenser, plug wires, dist. cap, points, rotor. I had it running fine about 1 month ago...now this !! ??

If anybody read my posts before, the original coil quit, the replacement coil was bad, now I have another replacement coil on it. Again, it was running great till about 2 weeks ago. Had a nice warm day here so I decided to work on it. Thanks all.

What am I missing or do wrong ? This is driving me nuts.

Very possible cause is dirt in the carb. low speed jet....assuming that you have an original Carter W-1 carb.
Remove air cleaner. Place #3 spark plug wire on #4 spark plug and #4 wire on #3 spark plug. Start engine and mash down the gas pedal several times. This wiil cause the engine to back-fire through the carb. and blow the dirt out of the low speed jet.

Ohhhhhh ok thx will try that ! It is a rebuilt carb, probably original to the car and rebuilt ( it has the little rebuild tag on it ) or replaced sometime in the last 71 years. Thanks for advice. And I did a search and looked at lots of posts about idling.

Clement,

Please let us know if the backfiring solved your problem.

Thanks, Mike

Clement,

Have you adjusted the idle mixture screw on the engine side of the carb? Or the accelerator rod? Or timing?

Just a thought or two,

Charlie

I hope not as those items will have no effect on your problem.

going to try right now...no...have not adjusted mentioned items. Fingers crossed

Tried the spark plug trick did it several times....lots of backfiring.idles ok...not perfect at all..better....still dies...probably need to do it more....ugh...

Could also have a vacuum leak such as the rubber wiper hose or cracked carbuetor to manifold insulator.

How old is the gas that you are putting into the carb?

Manifold gasket good.....will check wiper hose. Gasoline just 2 months old.

carb to manifold gasket good....wiper hose seems good.....did some more spark plug switching and blew out some more deposits.....still same situation when done...try it some more

Eliminate the wiper system completely by plugging the supply outlet to test. If you have tried the plug switching several times and it "helps" but is not a cure then either there is another problem or the carb needs a professional rebuild. I read the post where the gas is only a couple months old but did you check for possible water in the gas?

Hear is just a thought! The gas now a days has a minimum of 10% Ethanol added to the gas! Here is the following article I just found on the internet!

EPA Admits Ethanol Damages Engines This week 7/22/14 marks a victory for the latter camp, as the EPA has now publicly confirmed that ethanol does cause serious damage the engines.

According to the EPA, ethanol impacts motor vehicles in two primary ways. First … ethanol leans the [air/fuel] ratio (increases the proportion of oxygen relative to hydrocarbons) which can lead to increased exhaust gas temperatures and potentially increase incremental deterioration of emission control hardware and performance over time, possibly causing catalyst failure.

Second, ethanol can cause materials compatibility issues, which may lead to other component failures. What material compatibility issues would they be referring to? Ethanol has been known to wreak havoc on fuel systems, deteriorating plastic and silicone components such as hoses, fuel pumps and filters, gas tanks, and fuel injectors.

Among its other talents, ethanol also has the ability to etch aluminum and magnesium, as well as absorb moisture from the air, allowing a water/alcohol mixture in the fuel tank.

I have had a few leaf blowers rubber hoses destroyed plus my next door neighbor landscaper has had 2 high end chain saws engines destroyed from this E10 ethanol gas!

Plus a few months ago my 400 SB Chevy gas was dumping out on the garage floor and the next day tried to find the leak and now the gas was dumping in the oil pan.

Again that crap they put in the gas ate thru the rubber diaphragm in the mechanical fuel pump!

When you replace to any parts it NEEDS to be minimum 10% Ethanol rated including any rubber hoses, O-rings, etc.!

Rory
1934 Chevrolet Standard Roadster
1933 Ford 3 Window Coupe
1934 Ford 4 Door Sedan rolling frame under construction
1933 Ford 4 Door Phaeton

I have used gas with 10% ethanol in my old cars for the last 25 years and never had a problem. Due to health problems some was over two years old and the engines started and ran fine.
I do not let it sit all winter in my lawn mowers, etc. but it has never been a problem in my old cars. Also I have driven all over the country with the old cars using both non-ethanol and 10% ethanol and the engines always performed the same.

I have had nothing but problems for years with that junk Ethanol and hopefully the EPA will eliminate that crap in the near future.

Wow, I have used nothing but 10% ethanol since the early 1990s in my newer vehicles and never had a problem. I do avoid it in my old Chevys for 2 reasons, mainly the rubber diaphram in the fuel pump and one of my cars has a dirty fuel tank. Ethanol loosens up any crud in the fuel system and I had a problem with that in my '33 which sat out for years. I have used it in my '37 with no problems but it has been on the road constantly for it's entire life and has a clean gas tank. Maybe our ethanol here in Iowa is fresher or something but I will not use anything but ethanol in my newer vehicles if it is available. Sometimes on vacation I buy regular for my motorhome because it is cheaper or ethanol is not available but I don't see any difference in performance.

Gas with ethanol added will not generally be a problem with most vehicles if the gas tank is filled and the the vehicle driven regularly. There are two major issues, ethanol is polar and hydroscopic. 1. The polarity of ethanol can result in the molecule penetrating many elastomers (aka rubber) which can either swell or deteriorate the material or both. 2. Polar molecules have a positive charge on one side and negative on the other. H2O is also polar. So ethanol attracts water (hydro [water} scopic [seeking]. The water/ethanol molecule can act as an agent to loosen deposits. That produces solids that can plug small openings. Over time the water/ethanol compounds will attack metals like brass, copper, steel, zinc. It takes time to form the secondary compounds and therefore more insoluble solids that can coat or plug up stuff.

There are additives put into gasoline blends by the gasoline distributors to reduce the negative effects but they are only effective for a limited time. That is the reason that personally added stuff, like SeaFoam, Sta-Bil can help.

End of chemistry lesson for today. Back to the why the '46 will not idle. My guess is crud plugging a small opening.

Thanks all. Will take off wiper hose and plug that outlet on manifold and try that. There has got to be some more gunk in carb, and yes, it might need a professional rebuild. Suggestions ? I know you have to be careful finding a good rebuilder...have read stories about " carb rebuild disasters "on other posts on here.

The poster above your post is a carburetor rebuilder that you can depend on.
If dirt is a problem that problem MUST be resolved before any carburetor work is done.

There are several companies that make brand new carburetors just bolt on and adjust jets!

It would also be a good idea to buy a rebuilding kit to rebuild your old one as a backup!

Plus another tip have a clear plastic inline gas filter near the tank and another clear filter near the carburetor. That way you can get a visual of how dirty your fuel is!

Here is one www.chevsofthe40s.com Carburetor-Replacement Item # 838939 37-67 Weighs 4.9300lbs.

They have models is made especially for Chevy 6 cyl engines from 1937-1967. This high quality replacement carburetor bolts right on the manifold; has the normal Chevy linkage, pre-jetted, and are all manual choke models. It will fit either the 216 or 235 engines without modifications, and also the larger 261 engines. 1 year warranty for parts and manufacturing defects. Made in the USA

Rory
1934 Chevrolet Standard Roadster
1933 Ford 3 Window Coupe
1934 Ford 4 Door Sedan rolling frame under construction
1933 Ford 4 Door Phaeton

Here is another source Kanter Auto Products Classic Antique Car Restoration Parts! I have bought brand new Carters and rebuild kits for my 34 Chevy!

www.kanter.com

Rory
1934 Chevrolet Standard Roadster
1933 Ford 3 Window Coupe
1934 Ford 4 Door Sedan rolling frame under construction
1933 Ford 4 Door Phaeton

Use a VCCA advertiser and member Dean Echols Chino Valley Az. 928-710-4325 deanechols@cableone.net

Thanks. I bought a rebuild kit from Chev's.....the plunger in it was completely wrong....too short and a rectangular shaped shaft...original was round....other parts looked good. I appreciate the input.....I will try Chevgene's trick again, also take off wiper hose and try that. I might try rebuilding it myself....can it be that hard to do ??? LOL Or send it out to your 1 of your suggested places.

and I have the original ( or rebuilt ) fuel pump with the glass bowl. Gasoline clear and beautiful...no gunk at all. Also a fuel line filter was installed by previous owner near carb. Fuel clear and beautiful and no gunk .

Apparently your carburetor is not a 1946 as 1941 and later had the rectangular accelerator pump shaft. Earlier W-1 carbs had the round accelerator pump shaft. There are other differences depending on the actual application year.

It is also best to have another clear plastic fuel filter near the gas tank! That would be the first one to show signs of any contamination! You can never have to many fuel filters!
Rory

That is not exactly true. Too many fuel filters will tend to cause a gas flow restriction, especially when they become contaminated. Ideally, there should be a filter in the fuel pump and one either by the gas tank or by the carburetor, but not three filters in line.

Thanks, chipper. Well this just gets more and more interesting !!! What do I look for to tell me what year this crazy thing is anyhow ? Goodness knows what has been done to this thing in 71 years !!

This site is very helpful when identifying W-1 carbs;

http://www.thecarburetorshop.com/CarterChevroletW1.htm

Wow !!! Thanks ! At first glance, mine seems to be a 1938 or 1939 model. The people I bought the car from bought it in 1977...so it was 31 years old when they got it. He wrote down for me everything they did to it...no mention of anything about the carburetor.....so it must have been replaced , I am guessing, before they bought it. Who knows what previous owners did ?? LOL

All in all it still sould run and idle OK with an earlier carburetor.
The 1939 carb. will run richer at speed than a 1941. Also the low speed jet has a very tiny opening and almost must be removed for cleaning.
The throttle bore in a 1939 is 1 7/16" and 1 1/2" for 1941 and up. The 1941 and up also has an angle cut tube that you can see when the air cleaner is removed-in the center of the air horn.

Understood...sure once I get it figured out, ( cleaned, rebuilt, or replaced ) it should purr like a kitten as it did in the past. Correct...this carb does not have the tube in the air horn. Thx Chevgene and all of you fine people. Will let you know the results. Merry Christmas to you all...enjoy the day and your family time !!

Clement,

If you decide to rebuild your carburetor do a SEARCH of past posts for info. Also use the internet and the variety of manuals available to understand what is involved in a rebuild. I recommend making a video of the steps you use in removing the carb from your engine and dismantling the carb so you can correctly reassemble it.

Once you identify what carb is correct for your year I would look for the best source of a rebuilt one or a business that would rebuild yours. I would shy away from major part suppliers like Chevs of the 40's, Kanter. etc. that know little about carbs.

Do realize that a perfectly rebuilt carb may not be your problem, but in about a half an hour you could have the carb off your car and apart to check in the bowl for sediment and do a general inspection of its condition.

You may not know how to disassemble your carb. Why not buy one off of ebay and take it apart? 1941. ... Carter carb.

Here is a sample of some posts on this topic: Carter W - 1 carburetor tune up

Good luck, Mike

I would suggest you find a correct 1941-1948 carburetor rather than investing time and money in the one you have.

I agree. I had a 41 carb on my 37 and in ran perfect.

Thank you all again. I am tending toward purchasing a correct year carb. for my 1946. Your insight and suggestions are fabulous. I will do my research first though.

You did not mention HOW you know the intake gasket to cylinder head is "good".

Set the idle speed a "bit" higher to keep the engine running.

Take a propane torch, open the valve ..... BUT DO NOT LIGHT THE TORCH.

With the engine running AND the propane valve open, direct the nozzle of the propane torch between the intake and cylinder head, going from front of engine to rear of engine, by firewall.

If the RPM increases at any given point, with the propane test, the fast idle indicates a leak between the intake manifold and cylinder head.

If you decide to buy a replacement it might be worthwhile contacting Doyle Stokes. His contact info is listed in the Generator and Distributor classified ad section.
Good luck!

Thanks again experts !

Also, I misspoke with an incorrect term several posts back.....I meant to say the carburetor INSULATER, ( on mine it is a plastic piece between the carburetor and manifold ) seems to be good.....I said the manifold gaskets.....I was wrong in saying manifold gaskets, my apologies. It is in the teens here this week....pretty cold, and my garage is not heated. I have not checked yet taking the wiper hose off . Will update soon. Thanks

Just installed a rebuilt carburetor on it...same thing as before.....won't idle, when you push the choke in all the way it dies...Even when warmed up you have to pull choke out all the way or it won't start. I checked the operation of choke before I put air cleaner on. I am really hating this car...I have no idea what is wrong and no idea what to do now.

IF THE PROBLEM IS NOT THE REBUILT CRBURETOR (I SAID IF) you have a massive vacuum leak. Manifold to head possible.

You might want to take the car to your local mechanic and have him diagnose and repair the problem.

Is the vacuum cylinder for the vacuum gear shift hooked up" Is the vacuum cylinder hose (under the car) leaking? off? or?
There is a Y connction on the side of the intake manifold with one small hose running to the wiper motor and a metal tube runnig down to the rubber hose that is connected to the vacuum cylinder. If vacuum s assist had been removed/disconnected the line or hose may have been plugged and "plug" fell out or?

Thanks...will check vacuum lines, etc tomorrow....supposed to be 55 degrees here !!! Vacuum shift disconnected many years ago. I am so frustrated and stumped....thanks all. Driving me nuts...and yes, there is a old time mechanic shop 2 blocks from me.....might end up taking it there !!

That might be a good idea. With their diagnostic equipment they can probably find the issue right away and then repair it for you as well.

From a safety standpoint, a clear plastic or glass fuel filter is dangerous. The NSRA (National Street Rod Association) Safety Inspection Program won't pass a car with either one in the fuel system. The reasoning being they can be easily broken. Under the hood if it comes loose or is improperly mounted and comes in contact with something that can melt or break the filter, instant engine fire. If it's mounted under the car a rock or road debris can be thrown up by a tire and break the housing. May not cause a fire but I'm guessing the fuel running out will cause the car to slow or stall which if it happens in traffic can be dangerous. On my '46 Fleetmaster I have a metal in-line filter by the carb and another mounted on the frame rail in front of the rear axle and carry a spare. There not that more expensive than the plastic ones, and give you a greater piece of mind.

Thank you !! Ok..here is the latest.....The vacuum shift was removed many years ago.....the fitting on the manifold has 2 " ports"....1 is plugged very tightly ( the one that used to go to the vacuum shift ), the other has the wiper hose on that. I tightened every exhaust/intake manifold bolt...each 1 was 1/4 to 1/2 or a little more loose. Started car...ran for several minutes.....as soon as I pushed the choke in it just dies. Restarted several times , doing the same thing ( and I have to pull out choke each time ) and same results. It Will NOT idle !! Am I correct to think my next course of action would be to install new correct intake/exhaust manifold gaskets ? how difficult is this ? Thank you. BTW...I am a VCCA member...# 50675...updated my profile...maybe didn't do it right ?? My number and the logo doesn't show up ? !

The intake and exhaust manifolds are bolted together so will be removed as a unit.
The removing is easy enough but the difficult part is installing due to the alignment rings that line up the intake ports - manifold to head. I usually leave the carburetor installed and the exhaust pipe. and support the weight with a wire attached to the radiator support rod. Just unbolt and swing out the manifold.
Is the idle speed screw set up to keep the engine running at idle speed. Also the idle mixture screw (on left side) should be turned in and after bottoming out (don't turn in with too much force) turned out 1 1/2 turns and after enine is run and warmed-up fine tune for best idle.
To check the intake for leaks get the engine running and squirt oil around the intake to head connections. If leaking (that bad) it should cuuse the exhaust to smoke and run better because it is sucking in the oil.

I would try either Gene's or Bob1951chevy's ideas before changing the manifold gaskets. You need to identify the problem before you can fix it. If it does not suck in the oil or propane then look for another cause. Have you done a compression test?

Thank you. I will double check idle mixture and speed screws.......I believe they are ok. Thanks for advice on gaskets...my next project ! LOL Do I need to put any sealant, etc. on this ? Want to make sure I do it right the 1st time.

Thanks m006840.....just saw your comments.....ok...yes, you are right.....and have not done a compression test yet......will do that also. Thanks again. Update next week as I work on it.

Chipper,

Did by chance did you get that post about the pump rod backwards? The rectangular and round part?

Charlie


BTW: Always enjoy and am enlightened by your comments that give us the scientific low-down whenever a chemical question comes up. Thank you for your knowledge and willingness to share it.

OK...did a compression test according to the shop manual directions Sunday , Jan 21st. Readings : Cylinder # 1 90 ; # 2 75 ; # 3 95 ; # 4 75 ; # 5 70 ; # 6 70. According to shop manual..supposed to be 110 or better. This does not sound good. Of course...this didn't happen overnight. The engine ran fine until I had issues starting a few months ago. ( always started right up and purred like a kitten ) For those just joining in the original coil went bad, then the replacement coil went bad, now the 3rd coil...which seemed to be fine. New electrical components installed...( plugs, points, plug wires, condensor, points, dist. cap ) Just installed a rebuilt carburetor. But doing the same darn thing...it will start, run, but NOT idle. I just don't understand all this. As soon as I push the choke all the way in it just dies. Another question....when the motor is at correct idle, how wide does the bottom flapper valve in carburetor have to be open ? ( the small brass flapper that lets in the fuel/air mixture into the manifold ). It was suggested I must have a major vacuum leak. I tightened all the manifold bolts. Good grief !!!!!

While the compression is low on some cylinders it should still run at an idle but will be a rough idle. Also the compression has been low and it came on slowly as it has been low for some time.
How much should the throttle plate be open at idle. That depends and several things but the opening is determined by the idle speed adjusting screw on the throttle linkage. If idleing too slow turn screw clockwise to increase idle speed.
BUT the fact that it will run better with the choke out suggests that there is another problem. The choke makes the fuel/air mixture richer and the problem is it is too lean for some reason.
Note that when first starting engine in cold weather the choke must be partly out and the throttle pulled out to a fast idle speed.

I am also assuming that the valves are not sticking as that could cause rough or no idle and low compression and could come on suddenlty

Thanks. I understand your comment about the idle speed screw. If it is running too lean then that sounds like there is a problem with the carburetor ? Or does that just mean I have to keep playing with the air mixture screw adjustment ? Or the choke ? As far as I can tell the choke is operating correctly as far as flapper operation when choke open and closed. The running too lean is a new problem.

Did you try either of the suggestions on checking for a vacuum leak? Check the rotor for correct length. I had a similar situation and an incorrect rotor was causing the coil to max out and fail. Did the same with the new coil. Put the old rotor in and it started and ran fine. The rotor arm was too short giving a huge air gap for the spark to jump to the cap terminal. Also I would do another compression test with oil in the cylinders to determine if your low compression is due to rings or a valve problem.

Have not done their tests for vacuum leaks yet. Interesting about the rotor.....Will check but I doubt that's it. It seems correct. The whole situation is crazy. I just want to get it running correctly. It has given me nothing but problems. I am not that worried about the compression...it purred like a kitten when I 1st got it. Then it is one problem after another. I just need to get vacuum leaks fixed ( if there are any ) and get it to idle properly. Thanks.

vacuum advance canister? jim

Welcome to the wonderful world of old cars.

Sooo....I tried Chevgene's trick of squirting oil and it did what he said. I took off the manifolds today...glad I did.....the intake to exhaust manifold gasket needs replaced, the exhaust to tailpipe gasket was completely deteriorated , and yes the gaskets from block to manifold need replaced. Chuckle for all of you...the manifold heat flapper is installed correctly and moves properly....the counterweight was installed "upside down" ( flat part on top ) , and there is an excess glob of welding metal on it, ( where counterweight was welded onto the shaft ) preventing it from complete/correct movement. People do funny things !! Going to correct that, take both manifolds to a place I know and have them dunked , cleaned, primed, painted. Yay. Question....are we supposed to use any gasket cement on manifold to block, or intake to exhaust ? Or if not, just a little dab here and there just to hold it in place while manifolds are re installed and bolted on ?

No gasket cement or sealers are used. Are the manifold to head alignmsnt rings their. They go in the intake (round holes" AND MAKE SURE THE MANIFOLD HOLE IS IN PERFECT ALIGNMENT IS LINED UP WITH THE HOLES IN THE HEAD.THEY ARE A ROUND SPRINGY METAL RING ABOUT 31/4" WIDE AND SPLIT AND FIT IN THE RECESS AT THE ROUND OPENINGS IN THE HEAD and IN THE MANIFOLD.

Also, you might want to have the surfaces on both manifolds where they mate with the cylinder head machined flat....or at least have them checked to make sure that the surfaces are flat and not warped.

Ok. Yes rings are there. Will check flatness. Thank you both !! Will keep you all updated .

Clem,

MOM,

Is right on about the flatness of the mating elements of the head to manifolds. Only thing I would suggest is to not check them but merely take them on down to the machine shop and have them ground flat. They will more than likely need it.

Best,
Charlie

Clem,

For the sake of keeping the forum afloat and it from being augmented by the 1941 and 1942, If you ever get that old 46 idle, you may want to keep it to yourself. Such a post as your initial one helps the forum from becoming even more of a dead zone. This forum, most times can be sescribed as zzzzzzz. No one awake, sober, lucid, talkative, or anything else to counter the belief by the rest of us that the forum has either tanked or gone belly up. :)

41s and 42s should be included to the mix. I have wrote about many times but to no avail. No openmindness at the upper reaches of the club may be the reason. Who knows. :)

The 46-48a need help. Anyone should be able to see that.

Charlie

If you understand that one you are better than I am

Gene,

It's rather simple. 41s and 42s have more in common with the 46-48 than they do with the 37-40.

The 46-48 forum is so narrow that most questions posed are answered by in the 37-42 forum.

Accordingly, the narrow scope of the 46-48 forum tends to limit the traffic thereon. See easy.

Best,
Charlie

Ah ha ok ! thx.